Energy absorbing vehicle bumper bracket

ABSTRACT

A vehicle bumper system having a mounting bracket disposed between a vehicle frame and a bumper having angulated walls. The angulated walls are disposed at selected cross-sectional elevations, to avoid parallelograming under impact and provide maximum energy absorption. The mounting bracket includes a first surface and a second surface. The first surface of mounting bracket is adapted to be secured to the vehicle frame. The second surface of the mounting bracket is adapted to be secured to the bumper. The walls of the mounting bracket absorb an impact to the bumper.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application60/574,401, filed on May 26, 2004, which is incorporated herein byreference in its entirety.

TECHNICAL FIELD

The embodiments described herein relate generally to vehicle bumpersystems adapted to provide impact strength and energy absorption. Inparticular, the embodiments relate to an energy absorbing bumper bracketfor attaching a bumper to a vehicle frame.

BACKGROUND

Vehicle bumper systems generally include a bumper beam that istransversely mounted to a vehicle frame using a mounting bracket. Energyabsorption is particularly desirable during low speed bumper impacts(i.e., up to about 5 miles per hour), because an important purpose ofthe bumper system is to absorb energy before the vehicle frame itselfbegins to undergo damage. A limitation of many bumper beam mountingbracket designs is that they do not adequately absorb impact energyapplied to the vehicle bumper system. In many automotive applications,the bumper beam itself, and an optional polymeric foam applied to theface of the bumper beam, generally function as the sole energy absorbingcomponents in the bumper system. Thus, energy applied to the bumpersystem in excess of the energy dissipation capability of the bumper beamand polymeric foam is transferred through the mounting bracket into thevehicle frame. As a result, significant and expensive damage may occurto a vehicle's frame, even in relatively low speed bumper impacts.

Therefore, a need exists for a vehicle bumper system that includes anenergy absorbing mounting bracket that significantly contributes to theoverall energy dissipation capability of the vehicle bumper system.

BRIEF SUMMARY

The embodiments described herein are directed to an energy absorbingmounting bracket having angulated walls, the mounting bracket beingadapted for attaching a bumper to a vehicle frame. The angulated wallsare disposed at selected cross-sectional elevations to avoidparallelograming under impact and provide maximum energy absorption. Themounting bracket includes a first surface and a second surface. Thefirst surface of mounting bracket is adapted to be secured to thevehicle frame. The second surface of the mounting bracket is adapted tobe secured to the bumper. The walls of the mounting bracket absorb animpact to the bumper.

BRIEF DESCRIPTION OF THE DRAWINGS

The features and inventive aspects of the embodiments described hereinwill become more apparent upon reading the following detaileddescription, claims, and drawings, of which the following is a briefdescription:

FIG. 1 is a perspective view of a vehicle bumper system according to anembodiment of the present invention;

FIG. 2 is top view of the vehicle bumper system of FIG. 1;

FIG. 3 is another perspective view of the vehicle bumper system of FIG.1;

FIG. 4 is a side view of the vehicle bumper system of FIG. 1, showing abumper mounting bracket prior to attachment to a rail in a vehicleframe;

FIG. 5 is a perspective view of a vehicle bumper system mounting bracketaccording to an embodiment of the invention, showing a bumper-facing endof the mounting bracket;

FIG. 6 is a perspective view of the mounting bracket of FIG. 5, showinga rail-facing end of the mounting bracket;

FIG. 7 is a perspective view of a portion of the mounting bracket ofFIGS. 5 and 6 remaining after being cut by a first imaginary horizontalcutting plane, showing a W-shaped portion of the mounting bracket;

FIG. 8 is a perspective view of a portion of the mounting bracket ofFIGS. 5 and 6 remaining after being cut by a second imaginary horizontalplane, showing a U-shaped portion of the mounting bracket;

FIG. 9 is an end view of the rail used in the vehicle bumper system ofFIG. 1, showing the mounting bracket of FIGS. 5-8 superimposed over therail;

FIG. 10 is another perspective view of the mounting bracket illustratedin FIGS. 5-8; and

FIG. 11 is a perspective view of the mounting bracket of FIGS. 5-8 underload, showing the accordion-like collapse of the mounting bracket.

DETAILED DESCRIPTION

Referring now to the drawings, illustrative embodiments are shown indetail. Although the drawings represent the embodiments, the drawingsare not necessarily to scale and certain features may be exaggerated tobetter illustrate and explain an innovative aspect of an embodiment.Further, the embodiments described herein are not intended to beexhaustive or otherwise limit or restrict the invention to the preciseform and configuration shown in the drawings and disclosed in thefollowing detailed description.

Referring to FIGS. 1-4, a vehicle bumper system 20 is shown thatincludes a transverse bumper 22, a vehicle frame 24, and a pair ofmounting brackets 26 (only one mounting bracket is shown in FIG. 1) forremovably securing bumper 22 to the frame 24. In the illustratedembodiment, the frame 24 includes a pair of longitudinally extendingrails 28 (only one rail is shown in FIG. 1), each having a generallyU-shaped cross-section defined by a generally horizontal bottom wall 30and two generally vertical side walls 32 and 34. The longitudinal endsof each of the three rail walls 30, 32 and 34 have mounting flanges 38,40 and 42, respectively, for cooperative engagement with correspondingmounting surfaces of mounting bracket 26. The vehicle bumper system 20may be used as the front or rear bumper of a vehicle. It is understoodthat mounting brackets 26 may also be secured to the frame 24 having agenerally “I” shaped, square shaped, or any complex shapedcross-section.

As used in the description of the present embodiment, terms such as“horizontal” and “vertical” refer to the disclosed environment of aU-shaped rail that is oriented as shown, with the “open” side of therail routing upwardly. For ease of description, those terms have alsobeen used in the claims to discuss the interrelationship between therespective elements. Those terms are not intended to be limiting in anabsolute sense, i.e., with respect to the plane of the Earth's surface.It should be understood that the embodiments could also be used wherethe rail and bracket were both oriented in a different angular position,as long as the three adjacent walls of the rail were similarly orientedrelative to the bracket.

The bumper 22 is made of a structural material, such as steel, polyamideresin, or the like and may be configured in accordance with variousbumper designs known in the art. In the illustrated embodiment, forexample, bumper 22 is a curvilinear design having two relatively flatportions 44 adapted for engagement with the mounting bracket 26.

Referring to FIGS. 5-11, an embodiment of mounting bracket 26 is shown.In the illustrated embodiment, mounting bracket 26 includes a first end46 (see FIGS. 2 and 5) having mounting surfaces 48 and 50 adapted forconnection to bumper 22 and a second end 52 (see FIGS. 2 and 6) havingmounting surfaces 54, 56 and 58 adapted for connection to rail mountingflanges 38, 40 and 42, respectively. To facilitate easy connection andremoval of mounting bracket 26 from bumper 22 and rail 28, mountingsurfaces 48, 50, 54, 56 and 58 each include at least one hole 59A thatco-aligns with a corresponding hole 59B on mounting flanges 38, 40 and42 (see FIG. 1) and a hole 59C on bumper 22 (see FIG. 3). Holes 59A, 59Band 59C are sized to receive a removable fastener (not shown), such as anut and bolt arrangement, which is used to secure mounting bracket 26 toeach of bumper 22 and rail 28. Those skilled in the art will appreciatethat, for ease of economy of assembly, the bracket could be welded toone of the rail 28 and bumper 22, and bolted to the other.

Mounting bracket 26 is made from a material that provides the necessarystructure to attach and support bumper 22 on rail 28, yet is deformableto absorb impact energy applied to bumper 22. In a particularimplementation of one embodiment, mounting bracket 26 is made from drawquality steel (e.g., 2 mm in thickness) and is formed in a conventionalstamping operation as a single, continuous, piece of metal, withoutjoints. Alternatively, and without limitation, mounting bracket 26 maybe made from a polymeric material, such as plastic, or deformablecomposite materials.

As shown in FIGS. 5 and 6, mounting bracket 26 includes first and secondpairs of generally longitudinally extending walls 60 and 62,respectively, which are connected at their respective ends to the firstand second end mounting surfaces 48, 50, 54, 56 and 58. The second pairof longitudinally extending walls 62 is located transversely between thefirst pair of longitudinally extending walls 60 so that the first andsecond pairs of longitudinally extending walls 60 and 62 define agenerally W-shaped configuration at a selected imaginary horizontalcutting plane (see FIG. 7). The first pair of generally longitudinallyextending walls 60 converge toward the first end 46 of mounting bracket26, and the second pair of longitudinally extending walls 62 convergetoward the second end 52. a portion of the mounting bracket 26 defines agenerally W-shaped configuration an the imaginary cutting plane and aportion defines a generally U-shaped configuration.

With reference to FIG. 5, the first and second pair of longitudinallyextending walls 60 and 62 are also generally upwardly converging. In anembodiment, the first pair of longitudinally extending walls 60 extendupwardly to an optional longitudinally extending wall 63 that separateswalls 60. In contrast, the second pair of longitudinally extending walls62 intersect and connect with each other at a common upper end 64.

As shown in FIG. 5, mounting surfaces 48 and 50 at first end 46 ofmounting bracket 26 extend generally continuously between the upper andlower ends of both the first and second pairs of longitudinallyextending walls 60 and 62, and join together the first ends of one wallfrom each of the first and second pairs of longitudinally extendingwalls 60 and 62. Similarly, mounting surfaces 48 and 50 also jointogether the first ends of the other wall from each of the first andsecond pairs of longitudinally extending walls 60 and 62, to therebyform a portion of the generally W-shaped configuration.

As shown in FIG. 6, mounting surfaces 56 and 58 at second end 52 ofmounting bracket 26 extend generally continuously between the upper andlower ends of the first pair of longitudinally extending walls 60.Similarly, mounting surface 54 extends generally continuously betweenthe upper and lower ends of the second pair of longitudinally extendingwalls 62. Mounting surface 54 also extends between the second pair oflongitudinally extending walls 62, to thereby form another portion ofthe generally W-shaped configuration.

In an embodiment, the first pair of longitudinally extending walls 60extends upwardly beyond the upper ends of the second pair oflongitudinally extending walls 62. When so configured, the first pair oflongitudinally extending walls 60 and mounting surfaces 48 and 50 at thefirst end 46 of mounting bracket 26 define a generally U-shapedconfiguration at imaginary horizontal cutting planes through theportions of mounting bracket 26 above the common upper end 64 of thesecond pair of longitudinally extending walls 62 (see FIG. 8).

A common problem exhibited during a vehicle collision is that the impactforces generated on bumper 22 are not always centered on the bumper 22,and further are not always parallel with a longitudinal centerline ofthe vehicle. When imbalanced and off-centered impact forces occur, thereis a risk that the W-shaped portion of mounting brackets 26 may distortin a parallelogram-like fashion (so-called “matchboxing”), instead ofcrushing like an accordion. A parallelogram-like collapse isundesirable, since it typically absorbs much less energy than anaccordion-like collapse. The reason is because in a parallelogram-likecollapse, the mounting bracket material bends only at opposing ends ofthe longitudinally extending walls 60 and 62 (i.e., only bends at afront end near the bumper and at a rear end adjacent the vehicle frame).Contrastingly, in an accordion-like collapse, longitudinally extendingwalls 60 and 62 bend and crumple along multiple locations, includinglocations between their ends, with each of the bending locationsabsorbing energy from an impact.

To reduce the parallelogram or “matchbox” effect, the horizontalcross-section of mounting bracket 26 transitions from the generallyW-shaped configuration in the lower portion of mounting bracket 26 (FIG.7), to the generally U-shaped configuration in the upper portion ofmounting bracket 26 (FIG. 8). This transition is characterized by theconvergence of longitudinally extending walls 60 and 62 as they extendfrom their lower end to their upper end. Convergence of longitudinallyextending walls 60 and 62 reduces the individual lateral shifting ofwalls 60 and 62 that results when walls 60 and 62 are subjected toshearing/torsional forces, and inhibits each walls' failure in aparallelogram-like collapse. Walls 60 and 62 define a portion of abracket channel. In an embodiment, the walls 60 and 62 are angulated.Angulated means more than or less than ninety degrees.

In addition to reducing the tendency of longitudinally extending walls60 and 62 to “matchbox”, the transition from a generally W-shapedprofile to the generally U-shaped profile permits mounting bracket 26 touniformly load the generally horizontal bottom wall 30 and the twogenerally vertical side walls 32 and 34 of rail 24. As shown in FIG. 9,the convergence of the first pair of longitudinally extending walls 60allows imaginary longitudinal projections of walls 60 to intersect upperand lower portions of the generally vertical side walls 32 and 34 ofrail 28. Similarly, the convergence of the second pair of longitudinallyextending walls 62 allows imaginary longitudinal projections of walls 62to intersect bottom wall 30 of rail 28.

The portions of first and second pairs of longitudinally extending walls60, 62 that imaginarily project onto rail 28 may be defined by alongitudinally extending bead 70 in walls 60 and 62. Notably, each bead70 may be positioned to intersect rail 28 proximate a structurallysignificant portion of rail 28, such as the transition between bottomwall 30 and side walls 32 and 34, or the transition between side walls32, 34 and upper longitudinally extending flanges 43 of rail 28. Thus,the lower portion of mounting bracket 26 may be adapted to load thelower, closed portion of rail 28 and the upper portion of mountingbracket 28 may be adapted to straddle the upper, open portion of rail28, while uniformly loading side walls 32 and 34.

As will be appreciated, mounting bracket 26 significantly enhances theenergy management efficiency of bumper system 20, since mounting bracket26 is designed to collapse before the rail-buckling load is reached.Thus, in relatively low energy bumper impacts that exceed the energydissipation capability of bumper 22 alone, mounting bracket willcollapse and absorb the excess energy before any damage occurs in rail28. It is also understood that in one embodiment, the use of straight orcurved angulated walls form a bracket channel in the mounting bracket 26that provides uniform loading of the rail 28.

Among other features of the embodiments described herein, the W-shapedportion of mounting bracket 26 provides the surfaces necessary to securemounting bracket 26 to bumper 22 and rail 28 and, importantly, the wallmaterial needed to collapse in an accordion-like fashion to absorbenergy as bracket 26 is crushed during an impact. To inhibitparallelogram-like deformation of the W-shaped portion, the W-shapedportion of bracket 26 transitions into a U-shaped configuration as thefirst and second pairs of longitudinally extending walls 60 and 62upwardly converge. Further, the convergence of the first and secondpairs of longitudinally extending walls 60 and 62 allow imaginarylongitudinal projections of walls 60 and 62 to intersect structurallysignificant portions of the generally vertical side walls 32 and 34 andbottom wall 30 of rail 28, to uniformly load the walls of rail 28.

The embodiments herein have been particularly shown and described, whichare merely illustrative of the best mode for carrying out the invention.It should be understood by those skilled in the art that variousalternatives to the embodiments described herein may be employed inpracticing the invention without departing from the spirit and scope ofthe invention as defined in the following claims. It is intended thatthe following claims define the scope of the invention and that themethod and apparatus within the scope of these claims and theirequivalents be covered thereby. This description of the invention shouldbe understood to include all novel and non-obvious combinations ofelements described herein, and claims may be presented in this or alater application to any novel and non-obvious combination of theseelements. Moreover, the foregoing embodiments are illustrative, and nosingle feature or element is essential to all possible combinations thatmay be claimed in this or a later application.

1. An automotive vehicle bumper system comprising a transverse bumper, avehicle frame and a pair of mounting brackets for removably securing thebumper to the frame; the frame including a pair of longitudinallyextending rails each having a generally U-shaped cross-sectioncomprising a generally horizontal bottom wall and two generally verticalside walls, the longitudinal ends of each of the three rail walls havingmounting flanges for cooperative engagement with corresponding mountingsurfaces of the mounting bracket; an improved mounting bracket capableof controlled deformation and energy absorption in response to impactsto the bumper including: a first end comprising mounting surfacesadapted for connection to said bumper, and a second end comprisingmounting surfaces adapted for connection to said rail mounting flanges,said second end mounting surfaces being arranged and positioned forengagement with said three rail mounting flanges; first and second pairsof generally longitudinally extending walls, each of said longitudinallyextending walls connected at its respective ends to said first andsecond end mounting surfaces; said second pair of longitudinallyextending walls being located transversely between said first pair oflongitudinally extending walls so that said first and second pairs ofwalls define a generally W-shaped configuration at a selected imaginaryhorizontal cutting plane, with said first pair of walls convergingtoward said first end, and said second pair of walls converging towardsaid second end; and said first pair of longitudinally extending wallsbeing generally upwardly converging, and said second pair oflongitudinally extending walls being generally upwardly converging. 2.The vehicle bumper system of claim 1, wherein said second pair oflongitudinally extending walls intersect and connect with each other attheir upper ends.
 3. The vehicle bumper system of claim 1, wherein saidmounting surfaces at said first end extend substantially continuouslybetween the upper and lower ends of both said first and second pairs oflongitudinally extending walls, and join together said first ends of onewall from each of said first and second pairs of longitudinallyextending walls, and also join together said first ends of the otherwall from each of said first and second pairs of longitudinallyextending walls, to thereby form a portion of said generally W-shapedconfiguration.
 4. The vehicle bumper system of claim 1, wherein saidmounting surfaces at said second end extend substantially continuouslybetween the upper and lower ends of said first pair of longitudinallyextending walls, and also extend substantially continuously between theupper and lower ends of said second pair of longitudinally extendingwalls and between said second pair of longitudinally extending walls tothereby form a portion of said generally W-shaped configuration.
 5. Thevehicle bumper system of claim 1, wherein said first pair oflongitudinally extending walls extend upwardly beyond said upper ends ofsaid second pair of longitudinally extending walls, whereby said firstpair of longitudinally extending walls and said mounting surfaces atsaid first end of said bracket define a generally U-shaped configurationat imaginary horizontal cuffing planes through the portions of thebracket above said upper ends of said second pair of longitudinallyextending walls.
 6. The vehicle bumper system of claim 1, whereinimaginary longitudinal projections of said first pair of longitudinallyextending walls intersect upper and lower portions of said side walls ofsaid rail, and imaginary longitudinal projections of said second pair oflongitudinally extending walls intersect said bottom wall of said rail.7. The vehicle bumper system of claim 1, wherein said first and secondpairs of generally longitudinally extending walls include a bead,wherein imaginary longitudinal projections of each bead intersect saidrail proximate a structurally significant portion of said rail.
 8. Thevehicle bumper system of claim 1, wherein said bumper bracket is formedas a single, continuous, piece of metal, without joints.
 9. A vehiclebumper system comprising: a mounting bracket adapted to be disposedbetween a vehicle frame and a bumper; first and second mounting surfacesof said mounting bracket adapted to be secured to said vehicle frame andbumper, respectively; first and second pairs of generally longitudinallyextending walls interconnecting said first and second mounting surfaces,said first pair of walls converging toward said first mounting surface,and said second pair of walls converging toward said second mountingsurface; said mounting bracket being adapted to absorb an impact to saidbumper by the deformation of said first and second pairs oflongitudinally extending walls.
 10. The vehicle bumper system of claim9, wherein said mounting bracket includes a generally W-section at afirst end.
 11. The vehicle bumper system of claim 9, wherein saidmounting bracket includes a generally U-section at a second end.
 12. Thevehicle bumper system of claim 9, wherein said mounting bracketcollapses generally uniformly at a predetermined load.
 13. The vehiclebumper system of claim 9 wherein said deformation is in the form of anaccordion-like collapse of said walls.
 14. The vehicle bumper system ofclaim 9 wherein said mounting bracket is formed from one of a steel,aluminum, polyamide resin and a plastic material, and is in the form ofa single, continuous, piece of material, without any joints.
 15. Thevehicle bumper system of claim 9 wherein each pair of said first andsecond pairs of generally longitudinally extending walls also convergein a direction generally perpendicular to the direction of convergencespecified in claim
 9. 16. A vehicle bumper system comprising: a mountingbracket adapted to be disposed between a vehicle frame and a bumper;first and second mounting surfaces of said mounting bracket adapted tobe secured to said vehicle frame and bumper, respectively; first andsecond pairs of generally longitudinally extending walls interconnectingsaid first and second mounting surfaces, said first pair of wallsconverging toward said first mounting surface, and said second pair ofwalls converging toward said second mounting surface; said mountingbracket including a generally W-section adjacent one of said first andsecond mounting surfaces, and a generally U-section adjacent the otherof said first and second mounting surfaces; said mounting bracket beingadapted to absorb an impact to said bumper by the deformation of saidfirst and second pairs of longitudinally extending walls.
 17. Thevehicle bumper system of claim 16 wherein said deformation is in theform of an accordion-like collapse of said walls.
 18. The vehicle bumpersystem of claim 16 wherein said mounting bracket is formed from one of asteel, aluminum, polyamide resin and a plastic material, and is in theform of a single, continuous, piece of material, without any joints. 19.The vehicle bumper system of claim 16 wherein each pair of said firstand second pairs of generally longitudinally extending walls alsoconverge in a direction generally perpendicular to the direction ofconvergence specified in claim 16.